X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=Data%2FIntSet.hs;h=a47244ff35c3a2eab3364a22467f7ad556337061;hb=e42f2d710c07784c71bf57fe64fcbfb2005f6900;hp=622082796a9eb459df059b02503b7c0677286d66;hpb=dbf490ac992de84156826d846b25ecfbc4346744;p=haskell-directory.git

diff --git a/Data/IntSet.hs b/Data/IntSet.hs
index 6220827..a47244f 100644
--- a/Data/IntSet.hs
+++ b/Data/IntSet.hs
@@ -94,6 +94,7 @@ import Data.Bits
 import Data.Int
 
 import qualified Data.List as List
+import Data.Monoid (Monoid(..))
 import Data.Typeable
 
 {-
@@ -159,6 +160,11 @@ data IntSet = Nil
 type Prefix = Int
 type Mask   = Int
 
+instance Monoid IntSet where
+    mempty  = empty
+    mappend = union
+    mconcat = unions
+
 #if __GLASGOW_HASKELL__
 
 {--------------------------------------------------------------------